5 Flushing toilets

Page last updated: November 2010

Over the years the toilet has developed into its present form, the flushing toilet. It has a flushing mechanism to wash the urine, faeces and toilet paper away with water. This type of toilet requires a constant and sufficient (enough) water supply.

The flushing toilet provides a comfortable, safe and hygienic method of sewage disposal. The force of the water from the flushing mechanism, which is called the cistern, washes the urine, faeces and toilet paper out into the septic tank or sewage system.

The flushing toilet consists of a seat on a pedestal pan made of vitreous china or metal and a cistern. Most modern cisterns are dual flush, so a bigger flush can be provided to get rid of faeces and a smaller flush can be given to get rid of urine and liquid wastes.
Fig. 2.7: Diagram showing the parts of the flushing toilet.

It is important that toilet cisterns work properly all the time. If they do not work, the sewage is left in the toilet pan. Sewage left in toilets will smell bad and will bring flies which can carry disease-causing germs to people. If people keep using the toilet without flushing it, the toilet pan will fill up with faeces and paper and will block.

If the cistern does stop working it must be repaired as soon as possible. However, the toilet can be flushed by pouring a bucket of water into the pedestal pan. This should be done every time the toilet is used until the cistern is fixed.

The most important part is the cistern. This begins the flushing process. Sometimes the cistern is set behind the wall in a duct or cavity to protect it from vandals.

5.1 Problems with cisterns

Cisterns can develop leaks which are caused by blockages or broken or worn parts. The parts which usually become worn or broken are the ball float, the inlet valve or the outlet valve.
Fig. 2.8: Diagram showing the parts of the cistern.

When frogs or rubbish find their way into the cistern they can stop parts, such as the ball float or the outlet valve, from working properly. For example, frogs sitting on the ball float arm can prevent the inlet valve from closing and cutting off the water when the cistern is full. All rubbish and frogs should be cleaned out of the cistern.
Fig. 2.9: Frogs and rubbish in the cistern can stop it from working properly.

Any of these problems in the cistern can cause an overflow of water. Modern toilet cisterns are made in such a way as to get rid of the overflow water without making a mess.

In some older cisterns this overflow of water drains to the toilet floor and is disposed of through a floor waste. This is a drain that will allow any overflow or other small amounts of water which-get onto the floor, such as when it is washed, to flow outside the building. However, more modern cisterns are designed to allow the overflow to drain down the flush pipe into the pedestal pan.

If there is water leaking from the outlet drain or there is water continuously flowing into the pan, this means there is a problem with the cistern.
Fig. 2.10:Water continually flowing into the pedestal pan means there is something wrong with the cistern.

Some possible reasons for this continual flow of water into the pedestal pan or overflow of water on to the floor are:
The inlet valve stays open and allows the water flow because:

the ball float is leaking and sinks

the float arm is not correctly adjusted to cut off the inlet valve

frogs are sitting on the float arm holding the float down

the inlet valve rubber is worn

Fig. 2.11: A crack in the ball float will cause it to fill up with water and sink. A leak in the ball float can often be fixed by filling the hole with a special glue.

When the ball float arm is not adjusted to cut off the inlet valve properly the water overflows into the cistern. The float arm can be adjusted so that it cuts off when the cistern is full.

The inlet valve is faulty, such as when it is worn, and allows water to flow continuously

The outlet valve is faulty, such as when rubbish stops it closing properly, and allows water to leak down the flush pipe

The outlet valve becomes coated with mineral deposits from hard water and will not close

The outlet valve becomes covered in slime and will not close

Fig. 2.12: A faulty inlet valve.

The inlet and outlet valves need to be checked occasionally. They sometimes need cleaning, adjusting or replacing.

5.2 Leaking flush pipes

Behind the toilet pan is a pipe which joins the pan to the cistern. It is called the flush pipe and brings the water down to the pan when the toilet is flushed. This pipe can sometimes leak at the pipe/pan connection. This wets the floor and wastes water. If there is a wet patch on the floor behind the pan and the cistern is working properly, check the rubber cone connection.
Fig. 2.13: Rubber cone connection.